It appears in the final Quicktime render. But it's inconsistent, not always shifting despite exactly the same text effect being used. It's driving me nuts. (As is the way FCP is messing up my audio levels keyframes, but that's another post).

[Jason Fisher-Jones]"When I add a simple text layer, the brightness of the shot is reduced slightly. When the text cuts off, the shot gets lighter. What gives?"
The default white on the text RGB at 100%, so they are not "Broadcast legal".
You can set R-G-B = 235 (instead of the default 255), or low the transparency of the text a bit (this is what I normally do).
rafael